INCREASED MORBIDITY ODDS RATIO OF PRIMARY LIVER-CANCER AND CIRRHOSIS OF THE LIVER AMONG VINYL-CHLORIDE MONOMER WORKERS

Objectives-To determine if there is an increased risk of admission to hospital for various diseases among vinyl chloride monomer (VCM) worke rs. Methods-2224 workers with occupational exposure to VCM were identi fied for occurrence of disease based on a search of hospital computer files on labour insurance. These data were compared with those of work ers manufacturing optical equipment and motorcycles from 1 January 198 5 to 31 March 1994. Cardiovascular and cerebrovascular diseases were u sed as reference diseases, and the age adjusted morbidity odds ratio ( MOR) was calculated. Results-A significantly increased risk of admissi on to hospital among VCM workers due to primary liver cancer (MOR 4.5- 6.5), cirrhosis of the liver (MOR 1.7-2.1),and other chronic diseases (MOR 1.5-2.0) was found. There were eight cases of primary liver cance r, all with heavy previous exposure to VCM. Another four cases of hepa toma in polyvinyl chloride (PVC) workers were found in the death regis try. Ten out of 11 cases of hepatoma, with detailed medical informatio n, were carriers of hepatitis B virus. The average latent period (20 y ears) was not different from other studies. Alternative agents of prim ary Liver cancer were largely ruled out, suggesting that the combinati on of hepatitis B and VCM may lead to primary liver cancer. Conclusion -There is an increased risk of primary liver cancer in workers exposed to VCM, although the incomplete coverage of the Labor Insurance Burea u data warrants cautious interpretation of the results. Further study exploring the synergistic effects of VCM and hepatitis B is also indic ated.